Coagulation Factor IX Activity Assay, Plasma
Use
The Coagulation Factor IX Activity Assay is useful for diagnosing deficiencies, particularly hemophilia B (Christmas disease). It is also used for assessing the impact of liver disease on hemostasis and investigating prolonged activated partial thromboplastin time. Factor IX is a vitamin K-dependent serine protease that is synthesized in the liver and participates in the intrinsic coagulation pathway. Congenital deficiency of factor IX presents as an X-linked recessive bleeding disorder (hemophilia B), characterized by symptoms such as hemarthroses, deep tissue bleeding, excessive bleeding with trauma, and ecchymoses. Acquired deficiency is commonly associated with liver disease, vitamin K deficiency, warfarin therapy, and rarely, inhibitors.
Special Instructions
Coagulation testing is highly complex and often requires multiple assays and clinical correlation. For this reason, consider ordering a Coagulation Consultation. Double-centrifuged specimens are critical for accurate results as platelet contamination can cause spurious results. If priority specimen, mark the request form and request a call-back. Coagulation Guidelines for Specimen Handling and Processing must be followed.
Limitations
Improper specimen collection and handling, inappropriate test selection, and interfering substances such as liver disease, warfarin therapy, or vitamin K deficiency may lead to decreased factor IX levels and cause diagnostic confusion. Additionally, this test has been modified from the manufacturer's instructions and is not cleared or approved by the US Food and Drug Administration. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements.
New York Approved
Methodology
Other (Optical Clot-Based)
Biomarkers
LOINC Codes
- 3187-2
- 3187-2
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Plastic vial
Collection Instructions
Specimen must be collected prior to factor replacement therapy. Collect using a light-blue top (3.2% sodium citrate) tube, centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom of the centrifuged vial. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or ideally, at or below -40 degrees C.
Patient Preparation
Patient must not be receiving Coumadin (warfarin) or heparin therapy.
Storage Instructions
Freeze at -20 degrees C or ideally, at or below -40 degrees C.
Causes for Rejection
Gross hemolysis, gross lipemia, and gross icterus.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |